1. Field of the Invention
This invention relates, in general, to electrostatic ink jet printers and more particularly to an ink jet printer in which a replaceable cartridge is used not only as the ink supply but also as the ink jet itself.
2. Prior Art
In the past, electrostatic ink jets contained a supply of conductive ink together with an ink jet, a metallized surface upon which paper could be placed and a high voltage supply connected between the conductive ink and the metallized surface. Upon application of the voltage differential, the ink was drawn from the ink jet toward the metallized surface. Of course, since the paper was interposed between the ink jet and the metallized surface, the ink was deposited on the paper so long as the voltage was applied. Either the paper or the ink had to be moved in order to write any comprehensible information.
Many problems existed with such a system. For example, since the ink supply had to be replenished, the container had to include some opening means. Such an opening, of course, invited the entrance of dirt, which, it is readily apparent is diastrous to the passage of ink through an extremely small jet. Further, it was also found that variations in the level of ink in the container, i.e., head variations, had profound variations in the density and in the quality of the printing. There were also many other disadavantages such as the messy job of refilling the ink container which itself could cause the entrance of dirt.